This research will investigate age-dependent changes in memory in rats and mice. The experiments are based on our recent findings that, in rats, the retention of newly acquired responses declines with age. The first series of experiments will examine retention performance of 60 day, 1 year and 2 year old rats tested in several types of learning tasks in an attempt to determine whether the age-related decreases in retention performance are due to changes in the ability to retain recently acquired information. A second series of experiments will examine age-related changes in the susceptibility of recently acquired responses to the modulating influences of hormones, drugs, and electrical stimulation of the brain.